Re: Hash Values in Custom Classes
Re: Hash Values in Custom Classes
- Subject: Re: Hash Values in Custom Classes
- From: Peter Lübke <email@hidden>
- Date: Sat, 26 Mar 2011 02:23:42 +0100
Thank you, Mike, for showing me I was taken away by my own fantasy
about hash...
Am 26.03.2011 um 01:22 schrieb Mike Abdullah:
It sounds like you're rather misunderstanding what -hash does.
Cocoa classes are free to cover the full range of possible hash
values.
In the meantime, I read some related posts on the list and had to
recognize this, too...Sorry, this was the first time I was looking at
hash values at all.
You can't have a value that "interferes" with the framework; at
worse you could reduce performance IF putting custom objects in the
same container as framework-provided classes. Even then you'd be
hard-pressed to do this regularly.
To be more detailed: my custom class and its subclasses are wrapper
classes containing file informations. They are based on FSRef rather
than using paths - I do a lot of lengthy iterations so paths are much
too fragile. I also heavily use NSSet to store instances, and I
wanted -isEqual: to be as fast as possible. So I thought I could just
return a unique hash value for each custom class and return
(FSCompareFSRefs (&ownRef, &otherRef) == noErr) for -isEqual:, thus
avoiding the need to *first* compare the objects' classes.
_______________________________________________
Cocoa-dev mailing list (email@hidden)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden